Farm Effluent Testing

Tests to determine the nutrient status of Effluent

About Effluent Testing

Effluent testing should be seen as an important part of nutrient management. The more nutrients that can remain on-farm, the more money will be saved by the farmer and the better it will be for the environment.

Effluent has historically been viewed as a waste product to get rid of, but in fact it is a valuable source of nutrients. It can be used as a fertiliser replacement for a significant portion of the farm which can save a lot of money that would usually be spent on purchasing and applying fertiliser. The concern over nutrients in the environment is increasing because routine monitoring by regional councils indicate that nutrient levels are trending upwards. Elevated nutrient levels in lakes, streams and rivers provide food for micro-organisms leading to poor water quality, algal blooms, and eventually eutrophication.

In an effort to address this problem, regional councils have imposed limits on the application of nitrogen containing fertilisers. In the Waikato, no more than 150 kilograms of nitrogen can be applied per hectare/year which includes effluent spreading.Therefore farm nutrient management is a win-win situation. Once the effluent nutrient composition is known, the farmer is then able to apply the nutrient amount actually required by pasture, without running the risk of over application and wasting valuable nutrients which, once it enters the wider environment, will cause huge problems.

Effluent Testing is covered by our Dairy Effluent profile. Of particular interest are the following parameters:

Test

Typical Concentration

Total Nitrogen

0.44 kg/m3

Total Phosphorus

0.08

Total Potassium

0.3

Total Calcium

-

Total Magnesium

-

Total Sodium

-

Total Sulphur

-

Reasons for using this test:

Dairy effluent has historically been seen as a waste product, however its nutrient value is increasingly being recognised, and has the potential to save farmers many thousands of dollars that would usually be spent on synthetic fertilisers, as well as saving the environment from the harmful effects of nutrient run-off.

Taking a Sample

If you are trying to determine effluent application rates using spreaders, it is very important to follow a consistent process when taking effluent from a pond. For example, it is preferable to stir the pond before removing the effluent to provide a more consistent effluent stream. It is also important to follow the instructions in the kit when determining the application rate. This involves collecting the effluent in a series of containers and calculating the applied effluent depth in mm. This can then be used to determine the effluent application rate.